One of the most annoying and difficult problems in the use of screws and fasteners is that of inserting and driving them, or in reverse order locating and removing them, in recesses or places where it is difficult to see the head or socket, and where in addition it may be difficult or not possible to use two hands or an auxilliary tool. In these situations, it is necessary, to start and drive the screw, to have a tool which will hold the screw itself, yet release it when necessary. In the case of locating and removing a screw in such a location, it is further necessary to have a tool which will enable the user to locate the screw and center the bit of the tool to register with the head, then also capture it dependably and withdraw it as it is unscrewed.
Many devices have been offered in an approach to solving this problem, or these associated problems, as summarized below. Most of them require two handed operation of the tool to lock or affix it to a screw head, are difficult to apply or perhaps jam themselves under the head after driving the screw home, will not fit in narrow recesses or depressions, or do not perform all the operations required. The proposed invention is designed, simply, to do more of these things better.
A widely distributed magazine in the United States, Popular Science (Times Mirror Magazines, 380 Madison Avenue, New York City) featured in its May 1982 issue a survey and summary article on the field of screwdrivers. This article begins on page 132, and summarizes various special type screws and tools associated therewith. On page 134 there is mention of various types of screw holders or starters considered as commercially available, with specific mention of the most common forms with spring fingers or leaves which must be engaged with the head, or those with a wedge or center leaf which turns and jams in a screw slot to hold the screw on the tool bit.
A number of patents have issued on various devices intended to address these associated problems, and reference will be made to the following United States Patents known to applicant herein to have issued. They are listed with names of patentees, and with assigned letters for ease of reference.
______________________________________ Ref. U.S. Pat. No. Patentee Date ______________________________________ A 355,392 Fellers 1887 B 601,188 Webster 1898 C 881,296 Chappel 1908 D 1,229,793 Ryan 1917 E 1,889,330 Humes, et al (1) 1932 F 1,925,385 Humes, et al (2) 1933 G 2,028,546 John 1936 H 2,566,673 Nygaard 1951 I 2,633,168 Mahaffey 1953 J 2,762,408 Baldwin 1956 K 2,952,285 Roosli 1960 L 2,954,809 Loewy 1960 ______________________________________
These patents teach a variety of methods for gripping or holding screws and fasteners, and at least one (H,) provides for a set of removable bits or heads to convert it to a variable size wrench also. Reference D, to Ryan, involves a bulky box-shaped holding structure with a thumb lever for engagement which could not be used in a confined space or recess. Some of the features disclosed are the relatively common leaf-spring fingers (described in the Popular Science article) which must be positioned with care to hold a screw head (References A, B, I, J and K); a split tube type gripping device (References C, E, F, G, and L); and various methods of activating the holding means, such as cams (References G and L) and double or triple sleeves or barrels which act upon each other (References E, F, H, J and K). Some aver that the device automatically releases its grip (References E, F and I), while others require two-handed or two-step operation to lock and/or unlock (References A, B, D, J and L).